Effect of Caffeinated Energy Drink on Muscle Endurance and Wingate Cycle Performance in Young Adults

Abstract

Caffeinated energy drinks have gained popularity in recent years. Caffeine has been shown to increase short-term muscle endurance and power output. PURPOSE: To determine the effects of a caffeinated energy drink on upper body muscle endurance and repeated Wingate cycle performance in young males and females. METHODS: Healthy young adults (n=15, 11 male, 4 female, ∼21yrs) participated in a cross-over design where they were randomized to supplement with a caffeinated energy drink (2mg/kg body mass caffeine) or isoenergetic, isovolumetric, non-caffeinated placebo, separated by ∼7 days. Muscular endurance (bench press) was assessed by the maximum number of repetitions over 3 sets (separated by 1-min rest intervals) at an intensity corresponding to 70% baseline 1-repetition maximum (1-RM). Three 30s Wingate cycling tests (load=0.075kp/kg body mass), with 2 minutes recovery between each, were used to assess peak power and average power output. RESULTS: The caffeinated energy drink significantly increased total bench press repetitions over 3 sets (caffeine= 34±9 vs. placebo = 32±8; p<0.05), with no greater effect on peak or average power (caffeine=701±124W vs. placebo=700±132W; caffeine=479±74Wvs. placebo=471±74W). CONCLUSION: The caffeine containing energy drink significantly increased upper body muscle endurance, but had no effect on anaerobic peak or average power in young healthy adults. Supported by Red Bull Canada.